Could not find a good way to reach a simple final goal, also asked to support with little results: would be nice to draw dotted lines with brush tool.
Just simple ones as I can do in Photoshop, I'd love to do that in Illustrator too.
Sounds weird it is not already doable!
Dotted line is quite easily done with dashed stroke. Set dash width to 0, adjust your gap and turn round caps on. Or do you want something more elaborate?